Biology II AP Review
Mrs. Anne Gill
[email protected]
Cy-Fair High School
Cy-Fair ISD
Water
 Polar~ opposite ends, opposite charges
 Cohesion~ H+ bonds holding molecules
together
 Adhesion~ H+ bonds holding molecules to
another substance
 Surface tension~ measurement of the difficulty
to break or stretch the surface of a liquid
 Specific heat~ amount of heat absorbed or lost
to change temperature by 1oC
 Heat of vaporization~ quantity of heat required
to convert 1g from liquid to gas states
 Density……….
Density
 Less dense as solid
than liquid
 Due to hydrogen
bonding
 Crystalline lattice keeps
molecules at a distance
Polymers
 Covalent monomers
 Condensation reaction
(dehydration reaction):
One monomer provides
a hydroxyl group while the
other provides a hydrogen to
form a water molecule
 Hydrolysis:
bonds between
monomers are broken by
adding water (digestion)
Carbohydrates, I
 Monosaccharides
 CH2O formula;
 multiple hydroxyl (-OH)
groups and 1 carbonyl
(C=O) group:
aldehyde (aldoses) sugar
ketone sugar
 cellular respiration;
raw material for amino
acids and fatty acids
Carbohydrates, II
 Disaccharides
 glycosidic linkage
(covalent bond)
between 2
monosaccharides
 covalent bond by
dehydration
reaction
 Sucrose (table sugar)
 most common
disaccharide
Lipids
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No polymers; glycerol and fatty acid
Fats, phospholipids, steroids
Hydrophobic; H bonds in water exclude fats
Carboxyl group = fatty acid
Non-polar C-H bonds in fatty acid ‘tails’
Ester linkage: 3 fatty acids to 1 glycerol
(dehydration formation)
 Triacyglycerol (triglyceride)
 Saturated vs. unsaturated fats; single vs. double
bonds
Proteins
 Importance:
instrumental in nearly everything organisms do; 50% dry weight of cells; most
structurally sophisticated molecules known
 Monomer: amino acids (there are 20) ~
carboxyl (-COOH) group, amino group (NH2), H atom, variable group (R)….
 Variable group characteristics:
polar (hydrophilic), nonpolar (hydrophobic), acid or base
 Three-dimensional shape (conformation)
 Polypeptides (dehydration reaction):
peptide bonds~ covalent bond; carboxyl group to amino group (polar)
Primary Structure
 Conformation:
Linear structure
 Molecular Biology:
each type of protein has a unique
primary structure of amino acids
 Ex: lysozyme
 Amino acid substitution:
hemoglobin; sickle-cell anemia
Secondary Structure
 Conformation:
coils & folds (hydrogen
bonds)
 Alpha Helix:
coiling; keratin
 Pleated Sheet:
parallel; silk
Tertiary Structure
 Conformation:
irregular contortions
from R group bonding
hydrophobic
disulfide bridges
hydrogen bonds
ionic bonds
Quaternary Structure
 Conformation:
2
or more polypeptide chains
aggregated into 1
macromolecule
collagen
(connective
tissue)
hemoglobin
Enzymes
 Catalytic proteins: change the
rate of reactions w/o being
consumed
 Free E of activation (activation
E): the E required to break
bonds
 Substrate: enzyme reactant
 Active site: pocket or groove
on enzyme that binds to
substrate
 Induced fit model
Membrane traffic
 Diffusion~ tendency of
any molecule to spread
out into available space
 Concentration gradient
 Passive transport~
diffusion of a substance
across a biological
membrane
 Osmosis~ the diffusion of
water across a selectively
permeable membrane
Water balance
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Osmoregulation~ control of water balance
Hypertonic~ higher concentration of solutes
Hypotonic~ lower concentration of solutes
Isotonic~ equal concentrations of solutes
Cells with Walls:
Turgid (very firm)
Flaccid (limp)
Plasmolysis~ plasma membrane pulls away from cell wall
D:\ImageLibrary1-17\08MembraneStructureAndFunction\08-11Osmosis.mov
Plasmolysis
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Turgidity
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Cell Division: Key Roles
 Somatic (body cells) cells
 Gametes (reproductive cells): sperm and
egg cells
 Chromosomes: DNA molecules
 Diploid (2n): 2 sets of chromosomes
 Haploid (1n): 1 set of chromosomes
 Chromatin: DNA-protein complex
 Chromatids: replicated strands of a
chromosome
 Centromere: narrowing “waist” of sister
chromatids
 Mitosis: nuclear division
 Cytokinesis: cytoplasm division
 Meiosis: gamete cell division
The Cell Cycle
 Interphase (90% of cycle)
• G1 phase~ growth
• S phase~ synthesis of
DNA • G2 phase~
preparation for
cell
division
 Mitotic phase
• Mitosis~ nuclear division
• Cytokinesis~ cytoplasm
division
Cellular respiration
 Glycolysis: cytosol; degrades glucose into
pyruvate
 Kreb’s Cycle: mitochondrial matrix; pyruvate into
carbon dioxide
 Electron Transport Chain and Oxidative
Phosphorylation: inner membrane of
mitochondrion; electrons passed to oxygen
* SHOW VIDEO
Photosynthesis
 Redox process
 H2O is split, e- (along w/ H+) are transferred to CO2,
reducing it to sugar
 2 major steps:
 • light reactions (“photo”)
 - NADP+ (electron acceptor) to NADPH
 -Photophosphorylation: ADP ---> ATP
 • Calvin cycle (“synthesis”)
 -Carbon fixation: carbon into organics
 SHOW VIDEO
A review of photosynthesis
DNA Replication
 Leading strand: synthesis toward the
replication fork (only in a 5’ to 3’ direction
from the 3’ to 5’ master strand)
 Lagging strand: synthesis away from the
replication fork (Okazaki fragments); joined
by DNA ligase (must wait for 3’ end to open;
again in a 5’ to 3’ direction)
 Initiation: Primer (short RNA
sequence~w/primase enzyme), begins the
replication process
 SHOW VIDEOS
Figure 16.15 The main proteins of DNA replication and their functions
Figure 17.25 A summary of transcription and translation in a eukaryotic cell
Figure 10.19 Destinations for Newly
Translated Polypeptides in a
Eukaryotic Cell (Part 1)
Figure 18.5 The lysogenic and lytic reproductive cycles of phage , a temperate phage
Bacterial genetics
 Nucleoid:
region in bacterium
densely packed with
DNA (no membrane)
 Plasmids:
small circles of DNA
 Reproduction:
binary fission
(asexual)
Operons, I
Def: Unit of genetic function consisting of coordinately related
clusters of genes with related functions (transcription unit)
 Repressible (trp operon):
 tryptophan (a.a.) synthesis
 promoter: RNA polymerase binding site; begins transcription
 operator: controls access of RNA polymerase to genes
(tryptophan not present)
 repressor: protein that binds to operator and prevents
attachment of RNA polymerase ~ coded from a regulatory
gene (tryptophan present ~ acts as a corepressor)
 transcription is repressed when tryptophan binds to a
regulatory protein
Operons, II
 Inducible (lac operon):
 lactose metabolism
 lactose not present: repressor active, operon
off; no transcription for lactose enzymes
 lactose present: repressor inactive, operon on;
inducer molecule inactivates protein
repressor (allolactose)
 transcription is stimulated when inducer binds
to a regulatory protein
The Origin of Life
 Spontaneous generation
vs. biogenesis (Pasteur)
 The 4-stage Origin of life
Hypothesis:
 1- Abiotic synthesis of
organic monomers
 2- Polymer formation
 3- Origin of Selfreplicating molecules
 4- Molecule packaging
(“protobionts”)
Evolution
 Evolution: the change over time of
the genetic composition of
populations
 Natural selection: populations of
organisms can change over the
generations if individuals having
certain heritable traits leave more
offspring than others (differential
reproductive success)
 Evolutionary adaptations: a
prevalence of inherited characteristics
that enhance organisms’ survival and
reproduction
November 24, 1859
Descent with Modification, I
 5 observations:
 1- Exponential fertility
 2- Stable population size
 3- Limited resources
 4- Individuals vary
 5- Heritable variation
Descent with Modification, II
 3 Inferences:
 1- Struggle for existence
 2- Non-random survival
 3- Natural selection (differential
success in reproduction)
Population genetics
 Population: a localized group of individuals
belonging to the same species
 Species: a group of populations whose individuals
have the potential to interbreed and produce fertile
offspring
 Gene pool: the total aggregate of genes in a
population at any one time
 Population genetics: the study of genetic changes
in populations
 Modern synthesis/neo-Darwinism
 “Individuals are selected, but populations evolve.”
Hardy-Weinberg Theorem
 Serves as a model for the
genetic structure of a
nonevolving population
(equilibrium)
 5 conditions:
 1- Very large population
size;
 2- No migration;
 3- No net mutations;
 4- Random mating;
 5- No natural selection
Microevolution
 Genetic Drift
 Founder Effect and Bottle Neck
 Sexual Selection
 Gene Flow
 Mutations
 Natural Selection
Macroevolution: the origin of new taxonomic groups
 Speciation: the origin of new
species
 1- Anagenesis (phyletic
evolution): accumulation of
heritable changes
 2- Cladogenesis (branching
evolution): budding of new
species from a parent species
that continues to exist (basis of
biological diversity)
Reproductive Isolation (isolation of gene pools), I
 Prezygotic barriers: impede mating between
species or hinder the fertilization of the ova
 Habitat (snakes; water/terrestrial)
 Behavioral (fireflies; mate signaling)
 Temporal (salmon; seasonal mating)
 Mechanical (flowers; pollination anatomy)
 Gametic (frogs; egg coat receptors)
Reproductive Isolation, II
 Postzygotic barriers: fertilization occurs, but the
hybrid zygote does not develop into a viable, fertile
adult
 Reduced hybrid viability (frogs; zygotes fail to
develop or reach sexual maturity)
 Reduced hybrid fertility (mule; horse x donkey;
cannot backbreed)
 Hybrid breakdown (cotton; 2nd generation
hybrids are sterile)
Modes of speciation (based on how gene flow
is interrupted)
 Allopatric: populations
segregated by a
geographical barrier; can
result in adaptive radiation
(island species)
 Sympatric: reproductively
isolated subpopulation in
the midst of its parent
population (change in
genome); polyploidy in
plants; cichlid fishes
Punctuated equilibria
 Tempo of speciation: gradual vs.
divergence in rapid bursts; Niles
Eldredge and Stephen Jay Gould (1972);
helped explain the non-gradual
appearance of species in the fossil
record
Constructing a Cladogram
 Sorting homology vs. analogy...
 Homology: likenesses
attributed to common ancestry
 Analogy: likenesses attributed
to similar ecological roles and
natural selection
 Convergent evolution: species
from different evolutionary
branches that resemble one
another due to similar
ecological roles
A Cladogram
Figure 32.4 A traditional view of animal diversity based on body-plan grades
Figure 32.6 Body plans of the bilateria
Figure 32.7 A comparison of early development in protostomes and deuterostomes
Plant Evolution
 Four groups of Land Plants
 bryophytes (mosses)
 pteridophytes (ferns)
 gymnosperms (pines and conifers)
 angiosperms (flowering plants)
 Plants: multicellular, eukaryotic, photosynthetic
autotrophs
 Terrestrial colonization:
 Vascular tissue
 The seed
 The flower
Figure 29.1 Some highlights of plant evolution
Characteristics that separate plants from algae
ancestors
 Apical meristems:
localized regions of cell
division
 Multicellular, dependent
embryos (embryophytes)
 Alternation of
generations
 Walled spores produced
in sporangia
 Multicellular gametangia
Seed Plant Reproductive Adaptations
 Reduction of the gametophyte: shift from haploid to
diploid condition; female gametophyte and embryo remain
in sporangia (protection against drought and ionizing
radiation on land?)
 Advent of the seed multicellular sporophyte embryo with
food supply and protective coat; heterosporous (two types
of spores): megaspores--->female gametophyte--->eggs;
microspores---> male gametophyte--->sperm
 Evolution of pollen: develop from microspores which
mature into the male gametophytes; resistant and airborne
for a terrestrial environment; eliminated water
(sporopollenin coats)
Angiosperm structure
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Three basic organs:
Roots (root system)
fibrous: mat of thin roots
taproot: one large, vertical root
Stems (shoot system)
nodes: leave attachment
internodes: stem segments
axillary bud: dormant, vegetative potential
terminal bud: apex of young shoot
apical dominance: inhibits axillary buds
Leaves (shoot system)
blade
petiole
Plant Organ Systems
 Dermal (epidermis): single layer of cells for
protection
 cuticle
 Vascular (material transport)
 xylem: water and dissolved minerals roots to shoots
 tracheids & vessel elements: xylem elongated cells
dead at maturity
 phloem: food from leaves to roots
and fruits
 sieve-tube members: phloem tubes alive at maturity
capped by sieve plates; companion cells
(nonconducting) connected by plasmodesmata
 Ground (photosynthesis, storage, support): pith and
cortex
Plant Growth
 Life Cycles
 annuals: 1 year (wildflowers; food
crops)
 biennials: 2 years (beets; carrots)
 perennials: many years (trees;
shrubs)
 Meristems
 apical: tips of roots and buds;
primary growth
 lateral: cylinders of dividing cells
along length of roots and stems;
secondary growth (wood)
Summary of primary & secondary growth in a woody a stem
PRIMARY
MERISTEMS
Protoderm
Apical
meristem
of stem
PRIMARY
TISSUES
LATERAL
MERISTEM
Epidermis
Primary phloem
Procambium
Secondary
phloem
Vascular
cambium
Primary xylem
Ground
meristem
Ground Pith &
tissue: Cortex
SECONDARY
TISSUES
Secondary
xylem
Periderm
Cork
cambium
Cork
Whole Plant Transport
 1- Roots absorb water and dissolved minerals from soil
 2- Water and minerals are transported upward from roots to
shoots as xylem sap
 3- Transpiration, the loss of water from leaves, creates a force
that pulls xylem sap upwards
 4- Leaves exchange CO2 and O2 through stomata
 5- Sugar is produced by photosynthesis in leaves
 6- Sugar is transported as phloem sap to roots and other parts
of plant
 7- Roots exchange gases with air spaces of soil (supports
cellular respiration in roots)
Figure 36.1 An overview of transport in whole plants (Layer 4)
Cellular Transport
 Water transport
 Osmosis; hyper-; hypo-; iso-
 Cell wall creates physical pressure:
 water potential solutes decrease; pressure
increase
 Water moves from high to low water potential
 Flaccid (limp, iostonic);
 Plasmolysis (cell loses water in a hypertonic
environment; plasma membrane pulls away);
 Turgor pressure (influx of water due to
osmosis; hypotonic environment)
Transport of Xylem Sap
 Transpiration: loss of water vapor from leaves
pulls water from roots (transpirational pull);
cohesion and adhesion of water
 Root pressure: at night (low transpiration),
roots cells continue to pump minerals into
xylem; this generates pressure, pushing sap
upwards; guttation
Plant symbiosis, I
 Rhizobium bacteria
(found in root nodules
in the legume family)
 Mutualistic: legume
receives fixed N2;
bacteria receives
carbohydrates &
organic materials
Plant symbiosis, II
 Mycorrhizae (fungi); modified
roots
 Mutualistic: fungus receives
sugar; plant receives increased
root surface area and increased
phosphate uptake
 Two types:
 ectomycorrhizae ensheaths
the root
 endomycorrhizae (90% of
plants) through cell wall but
not cell membrane
Overview of food processing
 1-Ingestion: act of eating
 2-Digestion: process of food break down
enzymatic hydrolysis
 intracellular: breakdown within cells
(sponges)
 extracellular: breakdown outside cells (most
animals) alimentary canals (digestive tract)
 3- Absorption: cells take up small molecules
 4- Elimination: removal of undigested material
Figure 41.17 Enzymatic digestion in the human digestive system
Homeostasis: regulation of internal environment
 Thermoregulation
maintain an internal
temperature within a
tolerable range
 Osmoregulation
regulating solute and
water balance (gain
and loss)
 Excretion nitrogen
containing waste
Regulation of body temperature
 Thermoregulation
 4 physical processes:
 Conduction~transfer of heat between molecules of body and
environment
 Convection~transfer of heat as water/air move across body
surface
 Radiation~transfer of heat produced by organisms
 Evaporation~loss of heat from liquid to gas
 Sources of body heat:
 Ectothermic: low metabolic rate, amount of heat generated is
too small to have an effect on the organism. Body Temp then
determined by environment
 Endothermic: high metabolic rate generates high body heat
Figure 44.21 The human excretory system at four size scales
Heredity
 Heredity: the transmission of traits from one generation to
the next
 Asexual reproduction: clones
 Sexual reproduction: variation
 Human life cycle:
 • 23 pairs of homologous chromosomes (46)
 • 1 pair of sex and 22 pairs of autosomes
 • karyotype
 • gametes are haploid (1N)/ all other cells are diploid
(2N)
 •fertilization results in a zygote
 Meiosis: cell division to produce haploid gametes
 Chi square problems
Alternative life cycles
 Fungi/some algae
 •meiosis produces 1N cells that divide by mitosis to
produce 1N adults (gametes by mitosis)
 Plants/some algae
 •Alternation of generations: 2N sporophyte, by
meiosis, produces 1N spores; spore divides by
mitosis to generate a 1N gametophyte; gametes
then made by mitosis which then fertilize into 2N
sporophyte
Spermatogenesis and Oogenesis
 Spermatogenesis is the making of sperm and it starts
in the seminiferous tubules. 4 viable sperm will be
made.
 Oogenesis is the making of an egg and it starts in the
ovary. Only 1 viable egg will be made.
 Between birth & puberty; prophase I of meiosis
 Puberty; FSH; completes meiosis I
 Meiosis II; stimulated by fertilization
 Know the 3 major differences between
Spermatogenesis and Oogenesis
Cytokinesis unequal
Sperm cells consistently produce sperm, females born with all
Oogenesis has long periods of wait
Figure 46.15 The reproductive cycle of the human female
Hormones
 Hormonal coordination of the menstrual
and ovarian cycles involves five hormones.
 Gonadotropin releasing hormone (GnRH)
secreted by the hypothalamus stimulate
the release of LH and FSH.
 Follicle-stimulating hormone (FSH)
secreted by the anterior pituitary.
 Luteinizing hormone (LH) secreted by the
anterior pituitary.
 Estrogens secreted by the ovaries and
stimulates ovulation.
 Progesterone secreted by the ovaries.
The Fertilized Egg & Cleavage
 Blastomeres~ resultant cells
of cleavage/mitosis
 Morula~solid ball of cells
 Blastocoel~fluid-filled cavity in
morula
 Blastula~hollow ball stage of
development
Gastrulation
 Gastrula~ 2 layered, cup-shaped embryonic stage
 3 Embryonic germ layers:
 Ectoderm~ outer layer; epidermis; nervous system, etc.
 Endoderm~ inner layer; digestive tract and associated organs;
respiratory, etc.
 Mesoderm~skeletal; muscular; excretory, etc.
 Invagination~ gastrula buckling process to create the...
 Archenteron~ primitive gut
 Blastopore~ open end of archenteron
Circulation system evolution, II
 Fish: 2-chambered heart; single circuit of
blood flow
 Amphibians: 3-chambered heart; 2 circuits
of blood flow- pulmocutaneous (lungs and
skin); systemic (some mixing)
 Mammals: 4-chambered heart; double
circulation; complete separation between
oxygen-rich and oxygen poor blood
Figure 42.3 Generalized circulatory schemes of vertebrates
Double circulation
 From right ventricle to lungs via pulmonary arteries
through semilunar valve (pulmonary circulation)
 Capillary beds in lungs to left atrium via pulmonary
veins
 Left atrium to left ventricle (through atrioventricular
valve) to aorta
 Aorta to coronary arteries; then systemic circulation
 Back to heart via two venae cavae (superior and
inferior); right atrium
Blood vessel structural differences
Capillaries
 endothelium; basement membrane
Arteries
 thick connective tissue; thick smooth muscle;
endothelium; basement membrane
Veins
 thin connective tissue; thin smooth muscle;
endothelium; basement membrane
Figure 42.8 The structure of blood vessels
Blood
 Plasma: liquid matrix of blood in which cells are suspended (90%
water)
 Erythrocytes (RBCs): transport O2 via hemoglobin
 Leukocytes (WBCs): defense and immunity
 Platelets: clotting
 Stem cells: pluripotent cells in the red marrow of bones
 Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia;
thrombus (clot)
Gas exchange
 CO2 <---> O2
 Aquatic:
 gills
 ventilation
 countercurrent exchange
 Terrestrial:
 tracheal systems
 lungs
Mammalian respiratory systems
 Larynx (upper part of respiratory
tract)
 Vocal cords (sound production)
 Trachea (windpipe)
 Bronchi (tube to lungs)
 Bronchioles
 Alveoli (air sacs)
 Diaphragm (breathing muscle)
Breathing
 Positive pressure breathing: pushes air into lungs (frog)
 Negative pressure breathing: pulls air into lungs
(mammals)
 Inhalation: diaphragm contraction; Exhalation:
diaphragm relaxation
 Tidal volume: amount of air inhaled and exhaled with
each breath (500ml)
 Vital capacity: maximum tidal volume during forced
breathing (4L)
 Regulation: CO2 concentration in blood (medulla
oblongata)
Respiratory pigments: gas transport
 Oxygen transport Hemocyanin: found in hemolymph
of arthropods and mollusks (Cu)
 Hemoglobin: vertebrates (Fe)
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Carbon dioxide transportBlood plasma (7%)
Hemoglobin (23%)
Bicarbonate ions (70%)
 Deep-diving air-breathers Myoglobin: oxygen storing protein
Lines of Defense
Nonspecific Defense Mechanisms……
Specific Immunity
 Lymphocyctes
•pluripotent stem cells...
• B Cells (bone marrow)
• T Cells (thymus)
 Antigen: a foreign molecule that
elicits a response by lymphocytes
(virus, bacteria, fungus, protozoa,
parasitic worms)
 Antibodies: antigen-binding
immunoglobulin, produced by B
cells
 Antigen receptors: plasma
membrane receptors on b and T
cells
Induction of Immune Responses
 Primary immune response: lymphocyte proliferation and
differentiation the 1st time the body is exposed to an antigen
 Plasma cells: antibody-producing effector B-cells
 Secondary immune response: immune response if the individual is
exposed to the same antigen at some later time~ Immunological memory
Self/Nonself Recognition
 Self-tolerance: capacity to distinguish self from non-self
 Autoimmune diseases: failure of self-tolerance; multiple sclerosis,
lupus, rheumatoid arthritis, insulin-dependent diabetes mellitus
 Major Histocompatability Complex (MHC): body cell surface antigens
coded by a family of genes
 Class I MHC molecules: found on all nucleated cells
 Class II MHC molecules: found on macrophages, B cells, and activated
T cells
 Antigen presentation: process by which an MHC molecule “presents’
an intracellular protein to an antigen receptor on a nearby T cell
 Cytotoxic T cells (TC): bind to protein fragments displayed on class I
MHC molecules
 Helper T cells (TH): bind to proteins displayed by class II MHC
molecules
Figure 43.10 An overview of the immune responses (Layer 4)
Ecology
 Components:
 abiotic~ nonliving chemical & physical factors
 biotic~living factors
 Population~ group of individuals of the same species in
a particular geographical area
 Community~ assemblage of populations of different
species
 Ecosystem~ all abiotic factors and the community of
species in an area
Population Growth Models
 Exponential model (blue)
• idealized population in
an unlimited environment
(J-curve); r-selected species
(r=per capita growth rate)
 Logistic model (red)
•carrying capacity (K):
maximum population size
that a particular
environment can support
(S-curve); K-selected
species
Population life history “strategies”
r-selected
K-selected (equilibrial)
(opportunistic)
 Long maturation & lifespan
 Short maturation & lifespan  Few (large) offspring;
 Many (small) offspring;
usually several (late)
usually 1 (early) reproduction; reproductions; extensive
no parental care
parental care
 High death rate
 Low death rate
Community structure
 Community~ an assemblage of populations living close
enough together for potential interaction
 Richness (number of species) & abundance…….
 Species diversity
 Interspecific (interactions between populations of
different species within a community):
 Predation including parasitism; may involve a keystone
species/predator
 Keystone species may not be abundant in the environment, but they will
exert a strong control on community structures; not by number, but by
niches. They are usually a predator.
 Competition
 Commensalism
 Mutualism
Interactions
 Interspecific (interactions
between populations
of different species
within a community):
 Predation including
parasitism; may involve a
keystone species/predator
 Keystone species may not be
abundant in the environment, but they will exert a
strong control on community structures; not by
number, but by niches. They are usually a predator.
 Competition
 Commensalism
 Mutualism
Relationships
 Trophic structure / levels~ feeding
relationships in an ecosystem
 Primary producers~ the trophic level
that supports all others; autotrophs
 Primary consumers~ herbivores
 Secondary and tertiary
consumers~ carnivores
 Detrivores/detritus~ special
consumers that derive nutrition from nonliving organic matter
 Food chain~ trophic level food pathway
Energy Flow, I
 Primary productivity (amount of light energy converted
to chemical energy by autotrophs)
 Gross (GPP): total energy
 Net (NPP): represents the storage of energy available to
consumers Rs: respiration
 NPP = GPP - Rs
 Biomass: primary productivity reflected as dry weight of
organic material
 Secondary productivity: the rate at which an
ecosystem's consumers convert chemical energy of the
food they eat into their own new biomass
Energy Flow, II
 Ecological efficiency: % of E
transferred from one trophic level to
the next (5-20%)
 Pyramid of productivity:
multiplicative loss of energy in trophic
levels
 Biomass pyramid: trophic
representation of biomass in
ecosystems
 Pyramid of numbers: trophic
representation of the number of
organisms in an ecosystem